package com.base.invoke.utils;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Random;

public class RandomGUID extends Object {

    private static Log logger = LogFactory.getLog(RandomGUID.class);


    public String valueBeforeMD5 = "";

    public String valueAfterMD5 = "";

    private static Random myRand;

    private static SecureRandom mySecureRand;

    private static String s_id;

    /*
     * Static block to take care of one time secureRandom seed. It takes a few
     * seconds to initialize SecureRandom. You might want to consider removing this
     * static block or replacing it with a "time since first loaded" seed to reduce
     * this time. This block will run only once per JVM instance.
     */

    static {
        mySecureRand = new SecureRandom();
        long secureInitializer = mySecureRand.nextLong();
        myRand = new Random(secureInitializer);
        try {
            s_id = InetAddress.getLocalHost().toString();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }

    }

    /*
     * Default constructor. With no specification of security option, this
     * constructor defaults to lower security, high performance.
     */
    public RandomGUID() {
        getRandomGUID(false);
    }

    /*
     * Constructor with security option. Setting secure true enables each random
     * number generated to be cryptographically strong. Secure false defaults to the
     * standard Random function seeded with a single cryptographically strong random
     * number.
     */
    public RandomGUID(boolean secure) {
        getRandomGUID(secure);
    }

    /*
     * 随机生成GUID码
     */
    private void getRandomGUID(boolean secure) {
        MessageDigest md5 = null;
        StringBuffer sbValueBeforeMD5 = new StringBuffer();

        try {
            md5 = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            logger.info("Error: " + e);
        }

        try {
            long time = System.currentTimeMillis();
            long rand = 0;

            if (secure) {
                rand = mySecureRand.nextLong();
            } else {
                rand = myRand.nextLong();
            }

            //这个stringbuffer可以是您需要的长；
            //md5哈希将始终返回128位。
            //你可以在这里更改种子以包含任何你想要的内容。
            //你甚至可以通过md5来传输一个文件，使得猜测它的几率至少和猜测文件内容的几率一样大！

            sbValueBeforeMD5.append(s_id);
            sbValueBeforeMD5.append(":");
            sbValueBeforeMD5.append(Long.toString(time));
            sbValueBeforeMD5.append(":");
            sbValueBeforeMD5.append(Long.toString(rand));

            valueBeforeMD5 = sbValueBeforeMD5.toString();
            md5.update(valueBeforeMD5.getBytes());

            byte[] array = md5.digest();
            StringBuffer sb = new StringBuffer();
            for (int j = 0; j < array.length; ++j) {
                int b = array[j] & 0xFF;
                if (b < 0x10)
                    sb.append('0');
                sb.append(Integer.toHexString(b));
            }

            valueAfterMD5 = sb.toString();

        } catch (Exception e) {
            logger.info("Error:" + e);
        }
    }

    /*
     * 转换成标准的GUID码 例如: C2FEEEAC-CFCD-11D1-8B05-00600806D9B6
     */
    public String toString() {
        String raw = valueAfterMD5.toUpperCase();
        StringBuffer sb = new StringBuffer();

        sb.append(raw.substring(0, 8)); sb.append("-"); sb.append(raw.substring(8,
                12)); sb.append("-"); sb.append(raw.substring(12, 16)); sb.append("-");
        sb.append(raw.substring(16, 20)); sb.append("-");
        sb.append(raw.substring(20));

        //sb.append(raw);
        return sb.toString();
    }

    public static void main(String[] args) {
        new RandomGUID(true);
    }

}
